To find the cubical contents of a water cylinder per stroke, in cubic inches, multiply the area of the piston in square inches by the length of stroke in inches. To find the contents in gallons divide this product by 231, and to find it in cubic feet divide the product by 1728.

Example. - What is the capacity per hour of a single-action pump with a water piston 6 in. in diameter and a 10-in. stroke, when the piston makes 60 strokes per minute?

If the water cylinder is filled at each stroke, the contents are A X L = (6X6X .7854) X 10 = 28.274 X 10 = 282.74 cu. in.

At 60 strokes per minute there will be 60 X 60 = 3600 strokes per hour. If the piston pumps 282.74 cu. in. per stroke, then for one hour it will pump

282.74 X 3600 = 1,017,864 cu. in. per hour or 1,017,864 ÷ 1728 = 589 cu. ft. per hour or 1,017,864 ÷ 231 = 4406.33 gal. per hour

To find the H. P. required to pump water to a given height, multiply the weight in pounds of water to be raised per minute by the height in feet and divide by 33,000; the quotient will be the H. P. required. The formula is:

H. P. = W X H / 33,000

Example. - Find the H. P. required to pump 4406.33 gal. of water per hour to a height of 40 ft. above the source of supply.

If a pump will raise 4406.33 gals, of water per hour, it will raise 4406.33 + 60, or 73.438 gals, per minute; and as 1 gal. of water weighs 8 1/3 lbs., 73,438 gals, weigh 73.438 X 8 1/3 or 611.983 lbs. This weight of water is to be raised 40 ft. high. Then by formula:

H.P = W X H / 33,000 = 611.983 X 40 / 33,000 = 24,479.32 / 33,000 = .741 H.P.